1. Field of the Invention
The present invention concerns a process for treating noxious gases and/or substances which are produced in a gas-insulated electrical apparatus by virtue of an electric arc in the event of a switching operation or due to corona discharge, and an apparatus for carrying out the process.
2. Description of Prior Art
At the present time, the requirements for electrical energy means that metal-cased, gas-insulated electrical equipment such as power switches, circuit breakers or isolating switches, bus bars or contact rails and the like that have been incorporated in transmission lines are rising. Electrical equipment or switching equipment is already known, which is encapsulated in a metal housing, with the insulation being provided by a gas which has a high level of dielectric strength and excellent arc-suppressing properties, preferably SF.sub.6 gas. Although such gases, and in particular, SF.sub.6 gas, have the desired properties referred to above, they also have undesirable properties. The gas in a power switch or a circuit breaker is subject to decomposition by the electric arc, when the switch is cut in and out. Part of the decomposed gas combines with metal vapor and forms a fine-grain powder comprising fluorine compounds. The other part of the decomposed insulating gas is a gas which is injurious to health such as SF.sub.4 and/or SOF.sub.2. Such decomposition also occurs, although to a lesser extent, in regard to a gas-insulated bus bar or contact rail, as a result of corona discharge, with small amounts of various injurious gases being produced.
By passing the gas through a weak alkaline solution, it is possible to neutralise injurious gas because the gas is acid. However, the part of the decomposed gas which is converted to the above-mentioned fine-grain powder cannot be removed from the metal-cased equipment in this way. If for example a piece of metal-cased equipment of this kind is dismantled for the purposes of maintenance and examined, there is the danger that noxious powder can come into contact with the body of the person examining the equipment, or can be drawn in with the intake of breath. Although there is the simple expedient of removing powder from the metal-cased equipment by pouring water or a weak alkaline solution into the equipment and using one of those liquids to wash out the equipment, such a process suffers from the following disadvantage. On the one hand, the operation of washing the equipment and the drying thereof which is subsequently required requires a considerable amount of time. On the other hand, washing the equipment in this way can have the result that the equipment or parts thereof suffer from rusting. It is then difficult to remove the rust because this can only be done by dismantling the equipment or parts thereof, removing the rust therefrom, and then re-assembling the equipment.